This invention relates to a clamp for the repair of a leak in a pipeline or other structure having a flanged joint. A typical clamp usually consists of two semi-circular clamp sections which are bolted together to form a clamp ring about the site of the leak at the flanges. Some form of seal is incorporated in the clamp sections to define an enclosed annular space between the clamp and the flanges. A sealant material is injected into this enclosed space, usually through a wall of the clamp, to complete the leak sealing operation.
This method of sealing off a leak is widely followed in the industry, and a variety of clamps are known and in use.
A typical leak repair clamp is shown in U.S. Pat. No. 3,550,638. Metal tubes 26, 28 are positioned in parallel grooves in the inner surface of each of the clamp sections. When the clamp sections are joined together around the pipeline flanges, the tubes are deformed to provide sealing engagement with the flanges and define the enclosed space into which the sealant is injected through a valve 45.
An alternative clamp configuration is shown in U.S. Pat. No. 3,467,141 which utilizes interior gaskets 26, 28 held in place by spring fingers 30. U.S. Pat. No. 3,603,616 shows a structure similar to that of the preceding patent, and utilizes a locating lug 38 for positioning the clamp at the gap between the pipe flanges.
In the clamp of U.S. Pat. No. 4,049,296, elastomer seals 20 are clamped in place in interior grooves in the clamp sections by retaining members 21. U.S. Pat. No. 4,240,650 shows another alternative form which utilizes three parallel grooves in the clamp, with no other sealing structure. U.S. Pat. No. 4,209,029 shows a variation which utilizes two clamps with facing annular grooves to define the enclosed annulus for receiving the sealant.
U.S. Pat. No. 3,152,816 shows another form of clamp which utilizes plates 35, 60 for positioning between the flanges underneath the clamp ring.
These various prior art designs suffer from various problems such as the requirement of additional loose parts, elastomer seals, separate seals or gaskets, special grooves, and the like. Such loose and separate parts or seals add cost and complexity to the clamp and are often lost in adverse conditions under which many such clamps are installed. Elastomer seals and gaskets are undesirable for many high temperature and chemical leaks which attack elastomers. Such a situation is common and leaks frequently reoccur after the seals break down. Also, the various seals in the prior art which define the enclosed annulus for the sealant, are contained within the clamp ring structure when installed on the pipeline, thereby preventing any access to the seal point of engagement between the clamp and the pipeline; such acess may be desirable to make adjustments on difficult leaks.
It is an object of the present invention to provide a new and improved clamp for repair of a leak in a pipeline which clamp does not require any springs, spring fingers or other seal retention/pre-loading means, nor any separate seals or gaskets or other separate components, nor any elastomer materials. It is another object of the invention to provide such a clamp which can utilize clamp sections having a simple continuous surface without any special machining for retaining grooves for gaskets, seals or the like. It is a particular object of the invention to provide such a clamp with a structure which leaves the seal point of engagement between the clamp and the pipeline accessible after installation so that the seal can be custom fitted by peening or the like.
These and other objects, advantages, features and results will more fully appear in the course of the following description.